Investigation of Solar Waste Sand as a Supplementary Raw Material for Ordinary Portland Cement Clinker Production

This investigation evaluated the suitability of solar waste sand (SWS), derived from recycled photovoltaic panels, as a raw material in clinker production. Raw materials were prepared, analysed, and used to design reference and SWS raw mix kneaded balls. The balls were subjected to sintering tests with varying peak temperatures; the clinker mineralogy was analysed using X-ray diffraction (XRD). The SWS raw mix contained 13.14% SWS with 78.31% and 8.55% of limestone and clay, respectively. The SWS clinker had 55.64 ± 2.26% C3S, 18.67 ± 1.27% β-C2S, 1.57 ± 0.35% CaOf, and 3.70 ± 1.41% MgOf at 1350 °C, all within recommended ranges. Minor oxides, including Na2O, K2O, and MgO, reduced the required sintering temperature relative to the typical 1450 °C, as expected. The presence of an amorphous layer suggested the optimal temperature may be around 1350 °C. Furthermore, the high Na2O content in the SWS clinker is believed to have helped stabilise β-C2S. Low C4AF and the absence of C3A might indicate its suitability as a clinker for sulfate-resistant cements. Incorporating SWS directly into the raw mix for clinker production is an innovative approach to both diverting solar waste from landfills and partially supplementing sand and limestone.